The purpose of this experiment is to discover more about tarantulas. We would like to share our experiences of studying and raising the tarantulas with our roommates. Introduction We began this study in order to learn more about tarantulas: their growth patterns and behavior. Our hypothesis was that we cold disprove Dyar's Constant. Dyar's Constant states that a tarantula will increase its size by 1.7 with each molt. We have been feeding the tarantulas regularly and monitoring their growth in comparison to their food intake. When they molt we hope to see if Dyar's constant holds true or not. We also plan to observe the varying methods of obtaining prey and whether this affects growth at all. On a behavioral note: we want to record data on a daily basis on the location of the spider in its container. The all have a constant temperature and humidity.
Relevance General Information about Spiders
Spiders are in the invertebrate arthropod class Arachnida and are in the order Araneida. Unlike insects, arthropods with six legs and tri-segmented bodies, spiders have eight legs and a bi-segmented body. Thus, spiders have their own arthropod class. The earliest spider fossils came from the Middle Devonian Period and were found in New York State. Today, there are about 34,000 known species of spiders. They range in size from about .5-90 millimeters (.02-3.5 in). The largest spiders are hairy mygalomorphs also known as tarantulas. Tarantulas are most commonly found in tropical climates and in the Americas.
Young spiderlings resemble mature spiders. However, they lack reproductive organs and are much smaller than the adult spider. As spiders grow, they shed their exoskeleton. That process is called molting. Spiderlings molt quite frequently. Male spiders molt two to eight times while female spiders can molt up to twelve times. Prior to the molting phase, spiders will refuse food and become inactive. The molting phase is a very vulnerable phase for spiders. During the molt Tarantulas lie on their backs or their sides. The carapace cracks and the spider emerges from the shell of the exoskeleton. The new shell is very soft and the spider is defenseless until it hardens.
Life Cycle and Mating
Male spiders have a pair of appendages called pedipalps that change
to form sexual organs. The tips of the pedipalps enlarge to hold sperm. Female spiders have an epigynum, which is a hard plate on the underside of the body. The ways that spiders mate vary greatly. Male spiders wander to find a mate. Once a female is found male spiders use pheromones and visual senses to see if the female is ready to mate. Some male spiders mate only once during their lifetimes. However, female tarantulas mate multiple times during their adult lives. After mating, the female spider will produce an egg sac made with protective silk. Some female spiders will produce one egg sac with thousands of eggs while others will produce several smaller egg sacs. After the sac has been created the female spider places the sac in a protected place or, carries it with her until the spiderlings are ready to be born. Some female spiders will take care of their young for the first stages of their lives but many species of spiders are independent from birth.
Food and Feeding of Pet Spiders/Tarantulas
Tarantulas eat a wide range of animals and are considered predators. Smaller tarantulas and spiderlings usually eat fruit flies, and small insects. Larger tarantulas can be fed large insects, like locusts butterflies and moths, or lizards, mice, rats and even birds. Tarantulas never eat the meat of their prey. They drink the fluids of the prey left after their venom has digested the innards of their prey. Spider and Tarantula attack strategies involve slowly creeping up on prey and attacking when the prey moves. Another strategy of spiders and Tarantulas is spinning silk to create a web, a trap door, and for tunnel spiders to use as motion detectors in the area outside of the tunnel. Tarantulas usually eat prey that is one fourth to one half of their size. When dealing with your own Tarantula, it is important to remember to only give the Tarantula prey that it can handle (not too big) and to be careful what you feed the Tarantula so it does not get poisoned by whatever the prey ate (like pesticides). If prey carcasses are left near the Tarantula, there is a possibility that mold will develop and cause serious respiratory problems and even death for the Tarantula.
This question affects us all in a broader way. For those of us in the group that routinely deal with the tarantulas we have had to overcome our previous fears and found new ones: dealing with them hurting themselves or us accidentally hurting them. Hopefully upon seeing
our new mastery over our ungrounded fears will demonstrate to our classmates that there is nothing to fear from these docile creatures.
Materials and Methods>
There are ten containers with dampened peat for moisture that house the tarantulas. All of the tarantulas have the same temperature conditions and the same relative humidity. They are each fed one cricket twice a week The data collected by the class will be simple to collect. They will monitor whether or not the crickets have been eaten since the time of feeding, observe their geographical placement in their respective containers and what , if any, behaviors the tarantulas are displaying. Each class member will choose a date following our presentation to observe the tarantulas.
Sunday, October 22 Feed
Wednesday, October 25 Feed
Sunday, October 29 Feed
Tuesday, October 31 Presentation/Students select day to observe
Wednesday, November 1 Feed
Sunday, November 5 Feed
Wednesday, November 8 Feed
Sunday, November 12 Feed
Wednesday, November 15 Feed
Sunday, November 19 Feed
Wednesday, November 22 Feed
Sunday, November 26 Feed
Monday, November 27 Begin conclusions on Final Discovery Lab Report
Sunday, December 3 Feed
Friday, December 8 Final Discovery Lab Report Due
*Daily observations will be made by either group members or students.
Foelix, Rainer F. "Biology of Spiders"
Massachusetts: Harvard University Press, 1982 pp. 221-231
Hale, Ray& Angela "The Cause and Effect on the Bite of Selenocosmia Lanipes"
Oct. 1999 BTS http://www.bts.ndirect.co.uk.selenocosmia.htm
Holmes, Mackenzie; Lindsay, Faith; Waterman, Jenn "Tarantula Anatomy" 2000
Gearheart, Todd "Beginners Guide to the Tarantula Keeping Hobby" http://www.bts.nidirect/co.uk.begginer.htm
Gallon, Richard "A Review: Substrates Used in Tarantula Vivaris"
Martin, Doug "Basic Tarantula Care" 1998
Martin, Doug " "Impact of Tarantula Defenses on Humans" 1998
Martin, Doug "Tarantula Terminology" 1998
Sherberger, Fred, Dr. "Keeping your Tarantula Healthy: A Quick Guide"
Modified from the Forum of the American Tarantula Society, Vol. 2, No.2, 1993.
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